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Wedge IMA D E = Distance traveled by the effort = L D R = Distance traveled by the resistance = T T 3.0 ft L 10.0 ft What is the IMA of the wedge on the right? This formula is different than formula sheet

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Screw IMA D E = One rotation of the effort arm = Circumference D R = Linear distance traveled during one rotation of the effort arm = Pitch 1/4 20 NC What is the IMA of the screw above if effort is applied by an 8.0in. long wrench? Pitch is 1/ threads per inch

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Screw IMA D E = One rotation of the effort arm = Circumference D R = Linear distance traveled during one rotation of the effort arm = Pitch 1/4 20 NC What is the IMA of the screw above if effort is applied by an 8.0in. long wrench? Pitch is 1/ threads per inch

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Work (W) The product of the force (F) applied to an object over a distance (d) in which the object travels as a result of the force Joule (j) is the base unit of work (Force and distance must be parallel to each other)

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Power Rate at which work is performed or energy is expended Watt is the base unit of Power One watt is equal to 1 joule of work per second (or N-M per sec) work time 1 lb = 4.45 N and 1 ft = m Not on formula sheet

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Mechanical Winch Power output: Work / time Power input: Voltage * current Efficiency = P out * 100 P in Not on formula sheet

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Project Example A motor lifts a 20 N weight a distance of 3 meters in 12 seconds. While lifting, voltage was recorded as 12V and current was 1.5 A. What is the motors efficiency?

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Project Example A motor lifts a 20 N weight a distance of 3 m in 12 seconds. While lifting, voltage was recorded as 12V and current was 1.5 A. What is the motors efficiency? Power output: Work / time: Work = Force * distance Power out = (20 N * 3 m)/12 sec = 5 N-m/s or 5 watts (must convert if given feet and lbs) Power input: Voltage * current Power in = 12V * 1.5 A = 18 watts Efficiency = P out * 100 = 5 watts/18 watts *100 = 27% P in

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Conservation of Energy Energy cannot be created or destroyed, but it can change from one form to another. Energy Efficiency: The ratio of the useful energy delivered by a dynamic system to the energy supplied to it Entropy: The loss of energy during conversion Energy Conversion Changing one form of energy to another

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Electrical Circuit A system of conductors and components forming a complete path for current to travel Properties of an electrical circuit include Voltage (force (pressure) that causes current to flow) measured in Volts; symbol is V Current (flow of electric charge ) measured in Amps; symbol is A Resistance (opposition of current flow) measured in Ohms; symbol is Ω

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Circuit Configuration Series Circuits Components are connected end-to-end. There is only a single path for current to flow. Parallel Circuits Both ends of the components are connected together. There are multiple paths for current to flow. Components (i.e., resistors, batteries, capacitors, etc.)

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Circuits Series – Current same everywhere – Resistance adds to total resistance – Voltage adds to total voltage Parallel – Voltage same everywhere – Current adds to total current – total resistance (R T ) is equal to the reciprocal of the sum of the reciprocal:

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Example: Series Circuit For the series circuit shown, use the laws of circuit theory to calculate the following: The total resistance (R T ) The current flowing through each component (I T, I R1, I R2, & I R3 ) The voltage across each component (V T, V R1, V R2, & V R3 ) Use the results to verify Kirchhoffs Voltage Law. VTVT + - V R2 + - V R1 +- V R3 + - RTRT ITIT I R1 I R3 I R2 What is the current?

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Design Team A team is a collection of individuals, each with his or her own expertise, brought together to benefit a common goal. -Conduct research to develop knowledge base -Stimulate creative ideas -Make informed decisions

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What is a Design Process? A design process is a systematic problem- solving strategy, with criteria and constraints, used to develop many possible solutions to solve or satisfy human needs or wants and to narrow down the possible solutions to one final choice. – ITEA Standards for Technological Literacy

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3. Generate and Research Ideas Generate and Compile the ideas Conduct interviews with those affected by the problem. Research solutions that may already exist; identify shortcomings and reasons why they arent appropriate to a given situation. Compile ideas and report findings to the team.

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4. Identify Criteria and Specific Constraints Cost Limitations Time Identify what the solution should do and the degree to which the solution will be pursued. Identify constraints (i.e., budget, time, etc.). Draft the Design Brief.

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5. Explore Possibilities Consider further development of brainstorming ideas with constraints and tradeoffs. Explore alternative ideas based on further knowledge and technologies.

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6. Select an Approach Review brainstormed information and answer any lingering questions. Narrow ideas down through a voting process, or by use of a decision matrix. Decide on final idea, usually through group consensus.

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7. Develop a Design Proposal Create working drawings Generate Design Explore the idea in greater detail with annotated sketches. Make critical decisions such as material types and manufacturing methods. Generate through computer models detailed sketches to further refine the idea. Produce working drawings so the idea can be built.

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8. Make a Model or Prototype Prototype Creation Make models to help communicate the idea and to study aspects such as shape, form, fit, or texture. Construct a prototype from the working drawings so that the solution can be tested. BUILD!

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9. Test and Evaluate the Design Using Specifications Prototype Testing Trial Runs Design experiments and test the prototype in controlled and working environments. Gather performance data; analyze and check results against established criteria. Conduct a formal critique to flesh out areas of concerns, identify shortcomings, and establish any need for redesign work.

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10. Refine the Design Modify design Rebuild prototype Make design changes; modify or rebuild the prototype. Make refinements until accuracy and repeatability of the prototypes performance results are consistent. Update documentation to reflect changes. Receive users critique to provide outside perspective in order to determine whether established criteria have been met.